Postgresql 中文操作指南

37.2. Data Types #

信息架构视图的列使用信息架构中定义的特殊数据类型。这些数据类型定义为普通内置类型的简单域。不要在信息架构之外使用这些类型，但如果应用程序从信息架构中进行选择，则应用程序必须对其做好准备。

The columns of the information schema views use special data types that are defined in the information schema. These are defined as simple domains over ordinary built-in types. You should not use these types for work outside the information schema, but your applications must be prepared for them if they select from the information schema.

这些类型为：

These types are:

  • cardinal_number

    • A nonnegative integer.

  • character_data

    • A character string (without specific maximum length).

  • sql_identifier

    • A character string. This type is used for SQL identifiers, the type character_data is used for any other kind of text data.

  • time_stamp

    • A domain over the type timestamp with time zone

  • yes_or_no

    • A character string domain that contains either YES or NO. This is used to represent Boolean (true/false) data in the information schema. (The information schema was invented before the type boolean was added to the SQL standard, so this convention is necessary to keep the information schema backward compatible.)

信息架构中的每一列都具有这五种类型中的一种。

Every column in the information schema has one of these five types.